Re: FS: Transco Y Relay

Andy G4JNT

It maybe worth considering a customised bit of drive circuitry;  one that pulls in at a high voltage than drops to a lower holding value - or a constant current supply.    Both manageable with 'Simple-Switcher' SMPSU  devices.


On 19 March 2016 at 12:34, ALANNOTTAGE@... [ukmicrowaves] <ukmicrowaves@...> wrote:

There could be a case for evaluating that in advance (and maybe with any model?), i.e. powering it up on the bench and checking the temp. rise.  It's possible that's how mine failed in it's previous life wherever.  It's on a cad-plated steel plate, but not anywhere near as big as below. 
-----Original Message-----
From: Paul paul@... [ukmicrowaves] <ukmicrowaves@...>
To: ukmicrowaves <ukmicrowaves@...>
Sent: Fri, 18 Mar 2016 18:21
Subject: Re: [ukmicrowaves] FS: Transco Y Relay

Hi Al

Follow up to the message I sent a few minutes ago. I also found this in the instructions for the JWM sequencer, "A word of caution related to RF relays that are always in a constant energized state. Most of these relays are not designed to be energized for long periods of time, and will require a good heatsink to dissipate the heat that can build up. Transco “Y” relays for example can be energized for several hours at a time when mounted to an aluminum plate about 12 inches square or so, by ¼ inch to 3/8 inch thick. To provide the best possible heat transfer, use transistor thermal heatsink compound when you mount the relays to the aluminum plate."

Paul G4DCV

On 17-Mar-16 16:47, ALANNOTTAGE@... [ukmicrowaves] wrote:
Chris made reference to the coil resistance of the relay.  I have an Amphenol relay with a 110VAC coil.  I believe it's R is ~550 ohms.  It's not to hand just now, but I will check it later.  Thanks to Peter for that rule of thumb - I will need to know that too at some stage!
I don't recall which book/mag/internet article I was reading recently, Paul (it could have been the VHF DX manual), but there was a reference to relay heat sinking.  The general thread was that if the relay was energised for RX, it would be a good idea to do so. 

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